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One of my 'bucket list' projects is a 12-string based on a 93%-size dreadnought shape. I have a bunch of spruce tops, a cedar top, and a bunch of b/s sets (black limba, walnut, laurel, EIR, oak). I'm soliciting suggestions that will work towards making something on the not-so-jangly side of acoustics out of the woods on hand.

Any comments or advice from the gathered multitude?

Thanks!

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Peter Havriluk

Build it with Engelmann and walnut or EIR, X brace, string it with extra lights and tune to concert pitch. It will be a virtual swamp of overtones, not jangly at all...it will ring forever.

Listen to Haans - he should know. My humble opinion after owning several commercial 12 strings and building two of my own is that you can change the sound a lot by the choice of body size, scale length, bracing, strings and tunings. Play as many as you can, look inside the ones you like (and the ones you don't like), do your string tension calcs carefully (you will probably end up with 200 - 225 pounds) and brace accordingly.

Two things: don't over build, and do compensate both the saddle and the nut for each string.

'Strength' is not usually an issue in guitars; stiffness is. Any top that is stiff enough will be more than strong enough. Stiffness goes as the cube of top thickness/brace height. If you figure a 12-string to be carrying double the tension of a six, with the same saddle height, then it needs to have a top that is twice as stiff. Making the top itself about 25% thicker than your six-string top would be with thew same wood and size, and the bracing 25% taller, with just a little added width, gets twice the stiffness with only a bit more than 25% more weight. The first 12 I made that way was the first guitar I'd ever played that I could not sing over. You don't need to add in more braces. The bridge and plate, of course, end up a bit bigger.

The octave strings need much different compensation at both ends from the regular ones. A lot of the 'crunchiness' of the usual 12-string sound comes from the dissonance introduced by the lack of proper compensation. The first 12 I made that was actually properly compensated was a revelation. The fingerboard had to be shortened by at least 3mm at the nut end, and the nut notched back more or less for most of the strings. For the saddle I have long been making a wide one, about 3/16", with a pair of ridges for the low E, A,D, and G strings that run at different angles (you can calculate the offsets or find them by experiment). The section at the saddle top is /\/\, and the ridges are notched out for whichever string is not supposed to touch there. The trough between the peaks is made with a triangle file. This allows for the break points of adjacent strings to be as much as 3-4mm apart and still be easy enough to make, and look as though you meant it.

When I got it strung up I was afraid the sound would be too smooth. The player liked it because it meant that he could record the A and B parts without having to stop and retune. Every string on every fret was within 3 cents of 'perfect'. If you want more crunch, just reduce the compensation a bit.

One last point: I really prefer to make 12s with 12-fret necks. It'd hard to make the neck enough stiffer to carry the extra tension, since you can't really make it deeper. Obviously, use good wood, and reinforce it well. Very few 12-string players work much over the body anyway.

I bought a Seagull Walnut 12 last year for education and comparison. It's a lovely instrument, and a shockingly good value, but it's not one I made. Playing (or in my case, torturing) instruments I am guilty of making sure warms the soul.

Thanks, folks.

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Peter Havriluk

The bottom part of this might be helpful (and informative)

https://umgf.com/string-tension-t5339.html#.VpFU2aNIi1s

And yes, I run the Elixer heavy (0.013) set on the ladder braced guitar, but that is 26.5 scale and tuned to C

the only thing I will add is this Martin uses 3 tone bars I found that you can't scallop 12 X braces but you can do a light scallop on the tone bars. I use a slightly larger bridge plate that is about 1/4 in wider than the bridge at .115 thick.
I used both 25.4 and 24.9 scales . They do sound great and like Alan said take the time to work your compensation

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I use 'tapered' braving anyway. I imagine you could scallop them, so long as you leave the braces at least 25% taller. Gore's 'two degree' rule should be helpful: the bridge should rotate forward about two degrees when you put the string tension on; more than that and it may be too weak.

Freeman, don't know if you have ever seen the 26.5" scale, strings for different tunings, but they might be of use to you...



They were done by an English builder named Brown or something like that.

I can get down to even A with the red set. I usually just tune to B though and modified a few of the strings...

Haans, thank you. I will print that out and put it in the case with my little Stella clone. Right now its tuned to open G about 4 or 5 steps down (don't really remember) and it just roars as a slide guitar.